by duygu kiyan, DIAS

Uncovering Hidden Heat beneath County Antrim

The GEMINI Magnetotelluric Survey Launches

23 June 2025

This week marks the launch of magnetotelluric (MT) fieldwork for the GEMINI project! While the 3D Consulting-geo GmbH field crew begins deployment in County Antrim, our DIAS team is setting up a base station near the low-noise environment of Gougane Barra. Over the next two months, we will be deploying MT stations at 120 sites across County Antrim, each one helping us see deep beneath the surface.

What is  Magnetotellurics?  Magnetotellurics—often shortened to MT— is a geophysical method used to explore the Earth's interior without the need for drilling. It is a passive geophysical technique, which means we do not send any energy into the Earth ourselves. Instead, we measure natural changes in the Earth’s electric and magnetic fields. These tiny, naturally occurring signals reveal a key physical property: how well the rocks beneath our feet conduct electricity.

Did you know?

The term ‘magnetotelluric’ comes from the combination of ‘magneto-’ referring to magnetic fields and ‘telluric’ meaning Earth currents.

Why does that matter? Every type of rock has a different resistivity, or resistance to electrical flow (the inverse of electrical conductivity). Some things, like salty water or metal-rich minerals, conduct electricity easily: they have low resistivity. Others, like dry granite or quartz, are much more resistant. But resistivity does not just depend on the type of rock. It is also affected by temperature and fluids in the rock’s pore spaces. That makes MT especially useful in places where these factors matter, such as geothermal areas. In other words, MT helps us locate hot water reservoirs and fractured, fluid-filled zones deep within the Earth’s crust.

How do we measure it? In the field, we set up two main types of sensors:

1. Magnetic sensors: These are wire coils, around 144cm long—called induction coils—that measure changes in the Earth’s magnetic field. We install them in three directions: north-south, east-west, and vertical.

2. Electric sensors: These are pairs of electrodes buried in the ground, spaced about 100 meters apart. They measure voltage differences caused by telluric currents—natural electric currents that flow through the Earth when the magnetic field fluctuates.

By recording how the electric and magnetic fields vary together, we can estimate resistivity beneath each station. Once all the data are collected, the next step is to create a detailed model of the subsurface.

What’s Next? The GEMINI MT survey is just getting started. Over the coming weeks and months, we will be uncovering new insights into the geothermal potential and geological structure of County Antrim.
Stay tuned for more updates, behind-the-scenes field photos, and a first look at what we are discovering beneath the surface!

Images: A magnetic coil being buried in County Antrim during last summer’s pilot study; Plan view diagram of the MT sensor layout (Schmoldt J-P. 2011, PhD Thesis)

DIAS is a GEMINI partner.

by Pete Murtagh, Climate Action Officer at Sligo County Council

Tread Softly

6 May 2025

Sligo Regional Sports Centre, Cleveragh is one of the demonstration sites in the GEMINI project. As part of a wider retrofitting programme at the centre, a geothermal energy system, using heat extracted from up to 300 metres below the surface, will be installed beneath the car park to provide secure, low carbon, sustainable heat for the building and the swimming pool.

“As far back as I can remember, I always wanted to be a geologist.”
And while that may not actually be true, it borrows the opening line from one of my favourite movies, which I thought would be a good way to start this blog post. So, here we go.

It was in January 2022 that Ken Russell from Atlantic Technological University (ATU) got in touch to wish me a happy new year. But that wasn’t all he wanted to tell me. He also said that he had been in contact with Geological Survey Ireland (GSI), and that they were actively looking for a demonstrator site somewhere in the north-west for a geothermal project. I immediately realised that there was a potential for some sort of genesis to this original proposal, a metamorphic potential even. I have always had an interest in geology, and in particular what benefits there can be from understanding the Earth beneath our feet. And I also knew that even if it didn’t come to me straight away, Sligo Co. Co. had enough property assets and buildings that surely one of them would be a suitable location for the project.

So, by the time Ken called me a couple of days later, it was the Regional Sports Centre at Cleveragh which had seen a relatively rapid uplift to the top of the list of potential candidates that he had provided.

The possibility of using geothermal heating was a subject that had been mentioned to me by the former Sligo Co. Co. Chief Executive, Ciaran Hayes. He had spoken about the potential that there might be at Sligo Race Course for geothermal, and how it could possibly be harnessed to provide the heat source for a district heating system for new or existing social or private housing in the greater Cleveragh area. Perhaps it was pie in the sky at the time, but lately it’s starting to look more like manna from a heaven beneath our feet.

Since then, we’ve seen the partners being selected, with the good folks in Codema leading the way, the funding application to SEUPB being carefully pieced together, before submission and success. And now we find ourselves right in the thick of it. Detailed plans are afoot, some results are already in, but there is a long, long way to go until we see the full benefit of the process that we have entered into.

Geothermal energy sometimes seems to be the forgotten, or underappreciated, sibling of the energy family. Where once we relied so much (and still do) on the other fossil energy siblings - coal, oil, gas, all from the depths of the Earth - perhaps now we can replace them, but in a more efficient way, in a way much kinder to the environment, to the climate and to the whole biosphere, by drawing up a different type of energy from below. One that can provide heat without pollution, and which is something we can harness rather than exploit. The efforts to decarbonise society have to start somewhere, so why not begin from the ground up?

Did you recognise the line?

GoodFellas (1990) directed by Martin Scorsese.

Sligo County Council is a GEMINI partner.

by Duygu kiyan & giuseppe Maggio, DIAS

Exploring the Earth beneath County Antrim

with the GEMINI Passive Seismic Array

24 April 2025

Having joined the GEMINI project at Dublin Institute for Advanced Studies (DIAS) in October 2024, Giuseppe Maggio immediately started scouting and permitting for seismic station installation in Co. Antrim, Northern Ireland.

In January, Giuseppe, along with Colin Hogg (Senior Technician at DIAS) and members of the Geological Survey of Northern Ireland, then began installing the passive seismic stations. These stations will record data for the next 18 months to capture naturally occurring ground vibrations — from distant ocean tides to local human activities such as traffic and industrial operations; from natural events like storms to minor and distant earthquakes. The seismic vibrations move at different speeds through rock layers of different density and temperature and reach the passive seismic stations at different times. The wave data can then be processed by scientists to image the subsurface.

The data collected from seismic stations across County Antrim will be analysed to give us a better understanding of the layers of rock beneath our feet — all the way down to 5 km below the Earth’s surface.

Did you know?

A teleseismic earthquake is a tremor caused by an earthquake that originates more than 1,000 km away from the recording station.

How do we collect the data? Keeping our sensors safe from water is crucial, so the team came up with a clever way to protect the electronics. Here is how it works: First, we dig a hole about 50–80 cm deep and 30 cm wide. We pour some concrete in the bottom to give it a solid base. Then, we place a plastic drum down into the concrete and fill the bottom of the drum with cement to make a nice, flat floor for the seismic sensor to sit on. Once the cement has dried, we carefully place the sensor inside, making sure it is perfectly level and pointing North — this helps us figure out which direction the seismic waves are coming from. After that, we hook up all the cables and seal everything up safely inside the drum. The cables run out to a connection box, which links the sensor to its power source — a solar panel (1.2 m by 0.8 m) and battery (12 Volt) setup — so it can keep working out in the field without a problem.

So far we have deployed 22 stations, 4 stations to go!

What does the data look like? The plots in the image show seismic data recorded by our station ANT21 during Storm Éowyn. The first plot displays how ground motion changed over time, revealing the storm’s seismic signature. The second plot, called a spectrogram, shows the frequencies of these signals — helping us see how the storm’s energy was distributed over time at different frequencies, as captured by ANT21. We can also see other signals created by nearby traffic, which highlights how seismometers not only detect natural events like storms but also everyday human activity, offering a unique look into the vibrations around us.

Giuseppe and I will be doing regular check-ups and data downloads from each seismometer about every 2 to 3 months to keep everything running smoothly. If you happen to spot us out in the field while we are installing or servicing the instruments (don’t worry — we always have the landowner's permission), feel free to come say ‘Hi’ and ask us about the project!

Images: After a sunny day out in the field, Giuseppe and Colin wrapped up the installations at two different stations. The setup is looking solid — with the waterproof black box keeping our batteries and cables safe and dry (Photo: Giuseppe Maggio); Seismic data from station ANT21 reveals ground movement caused by Storm Éowyn.

DIAS is a GEMINI partner.

by aoife braiden, rml ltd

It  seemed like a good idea at the time…

In a hotel bar in Berlin my colleagues Ana Luisa, Sarah and I sat with a beer each and two large pieces of A3 paper. It was October 2022 and we were attending the European Geothermal Congress, a large conference full of academic, government and industry people involved in all elements of geothermal energy from policy, to technology, to cutting edge research.

We had been discussing presentations from that day and how a new, large-scale geothermal energy project at home could help to demonstrate the technology and reduce carbon emissions. We now needed to get something down on paper and figure out how it would all fit together. In front of us was appearing a very large, disorganised collection of words like ‘toolkits’, ‘resources maps’, ‘online platforms’ ‘best practice’, ‘data’ as well as people that we thought might use these, such as ‘policymakers’, ‘educators’, ‘geological surveys’, ‘businesses’, ‘planners’, ‘researchers’ etc. We began connecting the words to see what emerged.

The three of us, and colleagues in Geological Survey Ireland (GSI), the Geological Survey of Northern Ireland (GSNI) and Codema, had recently been discussing a large-scale project to demonstrate the potential contribution geothermal energy could make to decarbonising the heat sector. Previous work by GSI and GSNI and others had identified multiple gaps that needed to be filled before we could develop a sustainable geothermal energy sector on the island.

For example, neither jurisdiction had published policy or regulations in relation to deep  geothermal (i.e. deeper than 500m and relevant for larger scale industrial, commercial and residential heating and cooling). Nor did either survey have comprehensive heat maps to help developers and installers assess their options. Planners and local authorities didn’t have the necessary information to be able to make decisions about managing this resource safely and sustainably, nor how to incorporate geothermal energy into their council energy plans. We needed economic assessments of geothermal energy, specifically for our island, and what kind of incentives or financial supports might be suitable to boost this sector.

Looking forward, if we were successful in filling these gaps, who was going to help roll it out? We had to consider apprenticeships, professional training and academic courses to build a cohort of skilled people to support the sector in the long term.

We were also conscious that you can have the most amazing technology, financial supports and highest quality data, but if you do not inform people about what you are doing and why, then you will not succeed in delivering impactful renewable energy solutions. Designing and facilitating open dialogue so that people feel free to engage, ask questions and participate in decision making would be a vital element of this project.

We set about sketching a map of what a large-scale demonstration project should include and what type of partners we would be required. We needed to be able to demonstrate to all kinds of stakeholders, and in a range of different scenarios, that geothermal energy is a clean, reliable, secure and (critically) a feasible option on the island of Ireland. We discussed the work already done by the two geological surveys, European colleagues and our own excellent researchers on the island (geologists, geophysicists, engineers, social and behavioural scientists, community engagement practices, policy experts etc) and how best to pull this all together.

As we spread the pages out in front of us, and tried to make sense of the word-spaghetti we had just created, we realised this was both exciting and intimidating in equal measure! But more importantly, delivering this project was essential if we were really going to make a contribution to our energy transition.  

And so, there in a Berlin bar, the GEMINI project began to take shape…

Aoife is Managing Director of RML Ltd, a GEMINI partner.